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Title: What Sets the Slope of the Molecular Kennicutt–Schmidt Relation?

Abstract

The surface densities of molecular gas, Σ H2, and the star formation rate (SFR), Σ *, correlate almost linearly on kiloparsec scales in observed star-forming (non-starburst) galaxies. We explore the origin of the linear slope of this correlation using a suite of isolated  galaxy L * simulations. We show that in simulations with efficient feedback, the slope of the Σ * – Σ H2 relation on kiloparsec scales is insensitive to the slope of the ρ * – ρ relation assumed at the resolution scale. We also find that the slope on kiloparsec scales depends on the criteria used to identify star-forming gas, with a linear slope arising in simulations that identify star-forming gas using a virial parameter threshold. This behavior can be understood using a simple theoretical model based on conservation of interstellar gas mass as the gas cycles between atomic, molecular, and star-forming states under the influence of feedback and dynamical processes. In particular, we show that the linear slope emerges when feedback efficiently regulates and stirs the evolution of dense, molecular gas. As a result we show that the model also provides insights into the likely origin of the relation between the SFR and molecular gas inmore » real galaxies on different scales.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]
  1. The Univ. of Chicago, Chicago, IL (United States)
  2. The Univ. of Chicago, Chicago, IL (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1510809
Report Number(s):
arXiv:1809.07328; FERMILAB-PUB-18-757-A
Journal ID: ISSN 1538-4357; 1715029
Grant/Contract Number:  
AC02-07CH11359
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 870; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; galaxies: evolution; ISM: kinematics and dynamics; methods: numerical; stars: formation

Citation Formats

Semenov, Vadim A., Kravtsov, Andrey V., and Gnedin, Nickolay Y. What Sets the Slope of the Molecular Kennicutt–Schmidt Relation?. United States: N. p., 2019. Web. doi:10.3847/1538-4357/aaf163.
Semenov, Vadim A., Kravtsov, Andrey V., & Gnedin, Nickolay Y. What Sets the Slope of the Molecular Kennicutt–Schmidt Relation?. United States. doi:10.3847/1538-4357/aaf163.
Semenov, Vadim A., Kravtsov, Andrey V., and Gnedin, Nickolay Y. Thu . "What Sets the Slope of the Molecular Kennicutt–Schmidt Relation?". United States. doi:10.3847/1538-4357/aaf163.
@article{osti_1510809,
title = {What Sets the Slope of the Molecular Kennicutt–Schmidt Relation?},
author = {Semenov, Vadim A. and Kravtsov, Andrey V. and Gnedin, Nickolay Y.},
abstractNote = {The surface densities of molecular gas, ΣH2, and the star formation rate (SFR), Σ*, correlate almost linearly on kiloparsec scales in observed star-forming (non-starburst) galaxies. We explore the origin of the linear slope of this correlation using a suite of isolated  galaxy L* simulations. We show that in simulations with efficient feedback, the slope of the Σ* – ΣH2 relation on kiloparsec scales is insensitive to the slope of the ρ* – ρ relation assumed at the resolution scale. We also find that the slope on kiloparsec scales depends on the criteria used to identify star-forming gas, with a linear slope arising in simulations that identify star-forming gas using a virial parameter threshold. This behavior can be understood using a simple theoretical model based on conservation of interstellar gas mass as the gas cycles between atomic, molecular, and star-forming states under the influence of feedback and dynamical processes. In particular, we show that the linear slope emerges when feedback efficiently regulates and stirs the evolution of dense, molecular gas. As a result we show that the model also provides insights into the likely origin of the relation between the SFR and molecular gas in real galaxies on different scales.},
doi = {10.3847/1538-4357/aaf163},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 870,
place = {United States},
year = {2019},
month = {1}
}

Journal Article:
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This content will become publicly available on January 10, 2020
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